World petroleum supplies are finite. Thus, as world petroleum demand has increased (84,337 M bpd worldwide in 2009; US Energy Information Administration), easily accessible reserves have been depleted. Furthermore, much of the world's proven conventional petroleum reserves are located in regions which are politically unstable. Accordingly, supplies of petroleum from such regions might be uncertain since production of petroleum or the transportation of petroleum products from such regions might be interrupted.
Bituminous sands, colloquially known as oil sands or tar sands, are a type of unconventional petroleum deposit. The sands typically comprise naturally occurring mixtures of sand, clay, water, and a dense and viscous form of petroleum known as bitumen. Oil sands reserves have only recently been considered to be part of the world's oil reserves, as higher oil prices and new technology enable oil sands to be profitably extracted and refined. Thus, oil sands are now a viable alternative to conventional crude oil. Oil sands might represent as much as two-thirds of the world's total “liquid” hydrocarbon resources, with at least 1.7 trillion recoverable BOE (barrel of oil equivalent) in the Canadian Athabasca oil sands alone.
Extra-heavy oil and bitumen flow very slowly, if at all, toward oil-producing wells under normal reservoir conditions. Accordingly, in certain oil recovery operations from oil sands, the oil is made to flow into wells by using in situ techniques that reduce its viscosity by injecting steam, solvents, or hot air into the sands. These processes typically use large amounts of water and require large amounts of energy relative to conventional oil extraction. Further, typical extraction processes applied to oil sands generate significantly higher amounts of greenhouse gases per barrel relative to the production of conventional oils due to the increased energy requirements for recovery of oil from oil sands.
In other oil sand mining operations, where oil sands are relatively close to the earth's surface, surface mining has been used to extract the oil contained therein. After removing the overburden (the soil covering the oil sands), the sands are mechanically excavated and transported to a refining facility.
In one surface-mining method, after excavation, hot water and caustic soda (NaOH) are added to the sand. The resultant slurry is piped to the extraction plant where it is agitated and oil is skimmed off the mixture. The combination of hot water, sodium hydroxide, a flocculant and agitation generally releases bitumen from the oil sand, and the oil floats to the top of separation vessels where it is separated. Then, the separated oil is further treated to remove residual water and fine solids before subsequent processing to convert the heavy oil to usable products.
Such conventional processes to extract oil from oil sands also employ mixing the oil sand with high pH water, and then aerating the resultant mixture with air to produce froth (see, e.g., Masliyah, J.; Zhou, Z. J.; Xu, Z.; Czarnecki, J.; Hamza, H.: “Understanding water-based bitumen extraction from Athabasca oil sands.” The Canadian Journal of Chemical Engineering 2004, 82, (4), 628-654). A slurry of high pH water and oil sand is placed in a primary separation cell (PSC). Agitation and introduction of air assists in separating oil from the oil sand, and creates a froth in which the oil is entrained. The froth is removed, deaerated, and sent to feed tanks for further treatment. The remaining sand, comprising residual oil not removed in the PSC, is treated as “middlings” or as bottoms using the same process for extracting oil from oil sands in the PSC (i.e., high pH water and aeration). The froth from these subsequent processes is recycled to the PSC. The overall enhancement of oil from the oil in the froth is approximately 60% by mass over the iterative removal steps.
About two tons of oil sands are required to produce one barrel (roughly ⅛ of a ton) of oil. After oil extraction, the spent sand and other materials are typically transported back to the mine for disposal. However, even with improved extraction processes, up to 10% of the oil in the oil sands can be left in the resultant tailings. Thus, the process is inefficient. The tailings can contain significant amounts of oil and other pollutants which must be disposed of in an environmentally sound manner. In conventional oil sand mining operations, this has resulted in large lagoons containing high levels of oil and other pollutants. Accordingly, there is a need for improved compositions and methods for extraction of oil from oil sands that are more efficient (e.g., can remove higher amounts of oil), use less energy, and produce tailings that are environmentally benign.
In addition, in conventional oil production processes, methods of enhancing oil recovery are known. These include, but are not limited to hydraulic fracturing of rock formations containing hydrocarbon deposits. In hydraulic fracturing operations, a fluid (e.g., water) which can comprise various additives (e.g., acids, rheology modifiers, detergents, gels, gas, proppant, etc.) is introduced into a rock formation under high pressure to fracture the rock formation. Such fracturing of a hydrocarbon-bearing rock formation effectively increases the surface area of rock exposed to a wellbore (i.e., along the fracture faces), and accordingly, allows more hydrocarbon to flow into the well bore. However, the viscosity of the oils contained in the formation can limit the utility of hydraulically fracturing rock formations which contain heavy oils. That is, if the viscosity of the oil is too high, increasing the surface area of the formation exposed to the well bore along the fracture might not significantly increase production rates. Accordingly, there is a need for hydraulic fracturing fluids which can enhance total oil recovery or increase oil production rates.
In addition, remediation of environmentally compromised sites (e.g., hazardous waste sites) is an ongoing challenge. For example, there are many sites where hydrocarbons (e.g., crude oil, coal tar, creosote, refined oil products) have been spilled or discharged into the environment. Such discharges can result in contamination of soil or water, and can contaminate groundwater supplies. Accordingly, such contaminated sites or waters (e.g., rivers, streams, ponds and harbors) require remediation to extract contaminants.
There are several known remediation technologies. One method comprises excavation of contaminated soil. However, remediation by excavation has traditionally been a “dig and haul” process, wherein contaminated soils are excavated and disposed of in landfills or destroyed by thermal treatments such as incineration. In the case of landfill disposal of contaminated soil, the problem of soil contamination is not resolved as the soil is relocated and moved to another location. In the case of thermal desorption, the hydrocarbon or other pollutants can be destroyed, but typically produces a large carbon footprint, which, in and of itself, is not an environmentally friendly process, since energy is required and greenhouse gases are produced.
Chemical treatment (e.g., oxidation) has also been utilized in the remediation of contaminated soil. This process comprises excavation of the contaminated soil, followed by chemical treatment to chemically modify or degrade the pollutants to potentially less toxic or hazardous forms. However, such methods can require large quantities of specialized chemicals to oxidize the contaminants, and can be ineffective at oxidizing certain pollutants.
Another remediation method comprises injection of a material into the soil to sequester contaminants, with a goal of immobilizing them and preventing them from migrating. For example, stabilization/solidification (S/S) is a remediation or treatment technology that relies on the reaction between a binder and soil to stop, prevent or reduce the mobility of contaminants. Stabilization comprises the addition of liquid or solid materials to contaminated soil to produce more chemically stable constituents. Solidification comprises the addition of liquid or solid reagents to a contaminated material to impart physical, for example, dimensional stability, so that they are constrained in a solid product and to reduce mobility of the contaminants. However, such methods might not be desirable since over time, the solids can break down or degrade, releasing the hydrocarbons or other pollutants back into the environment.
Accordingly, there is a need for cost-effective methods for extracting contaminants (e.g., hydrocarbons) from soils and other substrates at environmentally compromised or contaminated sites and for sequestering contaminants in situ in a cost effective manner.
There is also a need for improved compositions and methods for extracting or removing other undesirable substances from substrates, such as the removal of a protein, lipid, wax, fatty acid or fatty alcohol from a substrate such as fabric, skin or hair. For example, skin sebum contains bulky oils such as long chain fatty esters and triglycerides and can be difficult to remove. Sebum generally comprises a complex mixture of triglycerides, wax esters, squalene, sterol esters and free sterols produced by sebocytes (cells of the sebaceous glands in the skin) and secreted to the skin surface. An excessive amount of sebum on the skin can lead to undesirable skin effects. Similarly, an excessive amount of oils or grease in hair can lead to an undesirable appearance. Thus, there is a need for novel compositions and methods to remove excessive oils from the skin and hair.
The present invention meets these needs and provides related advantages.